Apologises if there has already been another thread about this but I'm getting a little bit confused about this one and you guys on here have always helped me before so here it is.

My work PC is currently rocking an Intel Dual Core E6500 in an ASUS P5kPL-AM EPU motherboard and theres been no real problems. However we've recently had a batch of Dell Optiplex 755's come in with the E6550 Core 2 Duo processors. I have the opportunity of replacing my cpu with one of these Core 2 Duo processors before all the machines get put out into the work place.

The question is though is there any point with this upgrade? Most of the work I do is usual school technician work: Microsoft office, Adobe work (photoshop), occasional audio/video editing

probably would work don't see why dell would not take the e6500. e6500 is slower more ghz does not mean faster. plus the e6500 has 1066 bus versus the e6550 witch has 1333mhz bus (which is why i think it would work in the dell). Also the e6550 has TWICE the L2 cache.

Clearly the E6550 is the faster CPU here and should work in your asus board.

I disagree with clearly its faster. Its 700mhz slower. Depends on if you overclock and what application you really run. Heres an e4700 (an underclocked e6500) compared to the e6550, you can see it wins a few tests and its only half the missing speed.http://www.anandtech.com/bench/Product/61?vs=63

well with out looking at bench marks it is clearly faster based on all around specs. interesting the e4700 really does just barley edge out the e6500 on a number of benches there has less cache and slower buss speed. I'd still bet the 6550 would be worth a go on the asus board specially if OCed.

I still say its application dependant. More clock speed or more cache. I ran an e2180 with 1mb cache at 3.8ghz for about a year and it worked great, going to a Q9650 at 3.5ghz wasn't as impressive as I hoped.

Moving on going to the e2500k was an amazing jump. Then again, better architecture, more cache, more clock (4.5ghz)

The E6500 is superior to the E6550.
It's 45nm, so it consumes less power and has greater overclocking headroom, if you choose to do so. If not, it's worth noting that the E6500 is clocked 700Mhz higher than the E6550. This is significant.
The 45nm Wolfdale cores also have small improvements that allow for slightly greater performance at the same clock speed compared to the 65nm Conroe processors.